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Author Topic: prop shaft on submerged drive hulls  (Read 3685 times)

Brigadair

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prop shaft on submerged drive hulls
« on: February 15, 2016, 08:58:25 PM »

hi all and happy new year etc!!!!




Just a quick question.


This one is related to submerged drive hulls.


I'm building a couple over these cold dark winter months.


What are the reasons for filling in the void between prop shaft and hull?


I've run most of my boats with the gap between prop shaft and hull filled in.




Or is it more beneficial to leave a gap say with just the Skeg supporting prop tube.


Any advice appreciated.


Thanks


Garry



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Den W

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Re: prop shaft on submerged drive hulls
« Reply #1 on: February 16, 2016, 09:58:25 AM »

  Ask Bernard ,  he will tell you
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Brigadair

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Re: prop shaft on submerged drive hulls
« Reply #2 on: February 28, 2016, 08:06:55 PM »

Thanks Den.


Have done.


What are your views?
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Den W

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Re: prop shaft on submerged drive hulls
« Reply #3 on: February 29, 2016, 08:14:55 AM »

when ever I install sub shafts I use flexis.and try to keep them as close to keel line as poss,almost parralell,leaving around 6" from prop to transom,placing rudder about 2" from transom ..worked exstreamly well on an old Esprit I had...(wish I still had it)  hopes this helps   regards  Den
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triumphjon

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Re: prop shaft on submerged drive hulls
« Reply #4 on: March 03, 2016, 11:55:43 AM »

i only have submerged drive on any of my models , always try to have as shallow an angle as possible , you need the thrust to push the boat along , too steep & it wants to push the bow down , you need the hull up onto the plane for best performance , as for infilling the gap between the stern tube and bottom of hull , it will aid in supporting the stern tube
 what did bernard suggest
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Brigadair

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Re: prop shaft on submerged drive hulls
« Reply #5 on: March 12, 2016, 08:23:01 PM »

Thanks guys for the advice, much appreciated.


I'm running the boat with gap between hull and shaft which I think is what Bernard advises.




Cheers


Garry
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triumphjon

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Re: prop shaft on submerged drive hulls
« Reply #6 on: March 13, 2016, 08:28:37 PM »

have you supported the outward tip of the tube ? i have "P"  brackets fitted to my own boats
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Brigadair

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Re: prop shaft on submerged drive hulls
« Reply #7 on: March 13, 2016, 08:41:36 PM »

Hi tri!


yes the end of the shaft is supported.


The shaft is supplied by Bernard, it comes complete with a quality welded "skeg".


Thanks for the info.
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triumphjon

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Re: prop shaft on submerged drive hulls
« Reply #8 on: March 14, 2016, 10:37:05 PM »

do you have any photos of the bernard supplied shafts , ive been finding it difficult to obtain shafts from prestwich over the last year
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Brigadair

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Re: prop shaft on submerged drive hulls
« Reply #9 on: March 15, 2016, 07:53:53 AM »

Hi

Sorry don't have a picture handy and not sure if Bernard is supplying them without boats???

They are 1/4" steel, with 5mm prop stud at prop end. The engine end has a brass hub which holds the ball race in place. The prop tube has a brass skeg hard soldered / braised on it. The Ballrace is held in place with a circlip which is handy to allow for easy removal and replacement of ball race if required.
Bernard's contact details are on the sales and wants page of BMPRS.co.uk..


I know the Prestwich ones are 5mm dia  and excellent quality also.

Cheers

Garry

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triumphjon

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Re: prop shaft on submerged drive hulls
« Reply #10 on: March 16, 2016, 11:23:09 AM »

ideally i could do with stainless steel shafts as i operate in salt water , normal steel is knackred within a couple of runs even when they get greased ! ill give him a call to see if hes able to supply shafts/ tubes without buying a whole boat ,  ive not seen bernard nor any of the old pegasus members in quite a number of years
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